[BossaNova31]

Hi Josh,

Yes the monoblocks allow me to switch between push pull and SET. I honestly love both modes for different types of music. When I crave more bass and slam I switch to PP using between 2-3 feedback (its adjustable between zero to 10db of neg feedback). For music where I want detail and midrange magic I go to SET mode with the same feeback setting. I probably listen 70% of the time in SET and the other 30% in PP, but I tell you the PP mode is really darn good in its own right. You lose very little of the SET intimacy but pick up a lot more power and body to the sound. 25 watts of PP 300b power thru my Omega Superhemps is literally enough to blow you out of the room - the Manleys have a surprising amount of drive for their stated power ratings.

What speakers are you looking to match your PP 300bs up to? Both the Omega Superhemp and Maxhemp would be excellent choices IMO. 

The JJs are supposedly good tubes and the price is certainly more reasonable. The only other tubes I have tried are the TJ mesh plate gold pins. They sound beautiful, but I only have a matched pair (I used them maybe 50 hours on my integrated 300b amp). Debating possibly getting a second pair of the TJ for now rather than a full quad of KR, but I really like what I have read about the KRs and know I will go there eventually.


      

[Frihed91]

My favorite:  Raytheon 6SN7GT flat plates (sometimes called a Type 1).  My next: NU 6SN7GT Grey glass.  The best balanced, no flaws tube: any Sylvania 6SN7W.

[BossaNova31]

Thanks for all the responses. Here is my quick opinion of the 4 different 6SN7 tubes I have tried in the driver stage of my Manley 300b PP/SET monoblocks:

1) OEM supplied Sovtek 6SN7 - inexpensive tube that gets the job done but really not much good I can say. Bass is pretty weak and the sound is somewhat lifeless.

2) Tung-Sol 6SN7 (new production) - scored a set of these for about $40 and they are a bit better than the Sovteks, but I felt the midrange was somewhat grainy. Didnt do anything for me.

3) 1950s RCA 6SN7 GTBs - Much smoother midrange and highs than the previous two, bass is a bit tighter but still somewhat weak.

4) 1940s Ken Rad VT-231 - The most expensive 6SN7s I have tried but worth every penny. Scored a NOS set from a highly rated Ebay seller for $125. They blew the others away and sound perfect for my taste. Everything improved over the RCAs, especially bass. A much fuller sound than the RCA and vocals just plain sounded better. Listening to one of my favorite Ray Charles CDs the sax definitely bopped and his voice had more presence and emotion. Had me running for all my favorite CDs in fact. 

Now, I'm sure there are other NOS 6SN7s that some would argue are better but these Ken Rads really were head and shoulders above the others I tried. Based on what others have said I may someday try a set of NOS Tung-Sol VT-231s, but no rush.